[6.0] 0777683d7 vdef: Centralize __has_feature(...) fallback

[Reza Naghibi]

commit 0777683d7f6ad648ad81119540365b5b6540650c
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Thu Apr 15 19:07:01 2021 +0200

    vdef: Centralize __has_feature(...) fallback
    
     Conflicts:
            lib/libvarnish/binary_heap.c

diff --git a/bin/varnishd/mgt/mgt_param.c b/bin/varnishd/mgt/mgt_param.c
index 2bf69a0e5..c87c891a6 100644
--- a/bin/varnishd/mgt/mgt_param.c
+++ b/bin/varnishd/mgt/mgt_param.c
@@ -43,10 +43,6 @@
 #include "vav.h"
 #include "vcli_serve.h"
 
-#if !defined(__has_feature)
-#define __has_feature(x)	0
-#endif
-
 struct plist {
 	unsigned			magic;
 #define PLIST_MAGIC			0xbfc3ea16
diff --git a/include/vdef.h b/include/vdef.h
index f76407f80..60d833c33 100644
--- a/include/vdef.h
+++ b/include/vdef.h
@@ -64,6 +64,10 @@
 		*(fdp) = -1;			\
 	} while (0)
 
+#if !defined(__has_feature)
+#  define __has_feature(x)	0
+#endif
+
 #ifndef __GNUC_PREREQ__
 # if defined __GNUC__ && defined __GNUC_MINOR__
 #  define __GNUC_PREREQ__(maj, min) \